You forgot what? That they had lots of warning the Hurricane was coming? Or the fact the city was built (and rebuilt) below sea level?

And that (by federal law) the Governor of the state has to request federal assistance. And the Governor of LA (while obviously overwhelmed) repeatedly failed to request that assistance, even when repeatedly prompted ("remember, the federal government can't help until you ask"). Notice that similarly hard-hit areas of MS recovered more quickly because the Governor there asked for federal assistance immediately.

Add to that the widely-held knowledge (predating the Bush, Clinton, Bush, and Reagan administrations) that the New Orleans levee system was not designed to withstand a direct hit by a Category 4 or greater hurricane.